Fluid actuated lock cylinder



Feb. 5, 1946. B. N. ASHTON E'rAL.

FLUID ACTUATED LOCK CYLINDER Filed March 9, 1943 ATTORNE 'Y rsienied Feb. s, 194e escasez ori-ica FLUID ACTUATED LOCK CYLINDER j v Benjamin N. Ashton, Kingston, and Nelson G. Kling, Great Neck, N. Y., assignors toElectrlcal Incorporated, New York, N. Y., a corporation of Delaware Application March 9, 1943, Serial No. 478,574

3 Claims.

The present invention pertains tohydraulic 'or pneumatic jacks. Its object is to provide a locking device for mechanically vlocking the piston of such a jack in its extreme positions of`movement so that upon completion of its stroke in one direction, it cannot be displaced; for instance, by the action of an external force, unless iluid pressure is admitted into the cylinder to produce a stroke in the opposite direction.

To that end the piston head and the cylinder ends are provided with corresponding recessed portions adapted to form, when in register with each other, two or more peripheral compartments. In the locked position, balls are received in said compartments so that one portion of each ball is held in the piston head and another in the cylinder end. The presence oi theie balls prevents any axial displacement of the piston head with respect to said cylinder. In the unlocked position, i. e., when said piston head travels along said cylinder, said balls are lodged in suitable recesses provided either in the former l or in the latter.

In addition, said piston head slidably carries an auxiliary elementcapable of relatively small axial displacements with respect to the same. Saidauxiliary element is subjected. to the same iiuid pressure as the piston and, consequently, whenever iluid pressure is admitted into the cylind'er said element will tend to travel in the same direction as the piston head. When, upon the completion oi a stroke, the piston head reaches one of its extreme positions in the cylinder, said auxiliary element will also be in one of the extreme positions which it can assume with respect to said piston head. In that position said auxiliary element will, by virtue of the structure of its axial end faces, displace said balls from the aforesaid recesses-in which they were 'lodged during the stroke of the piston head-push the same intohsaid compartments and lock them therein.

When fluid pressure is admitted for the return stroke of the piston said auxiliary element will be displaced rst-since the piston head is locked-and this will set the balls free. The forces exerted on said balls by the piston head when the same is subjected to fluid pressure will push said balls back into said recesses as soon of `a jack according the present invention,

' showing the piston in its locked position;

as they are set free, whereby the piston head is l unlocked and capable to travel along the cylinder.

Further features may be gathered from the following description oi' two embodiments oi. the present invention given by way of example vand lillustrated in the accompanying drawing.

Fig. l is la longitudinal view partly in section Fig..2 is an enlarged section of adetail of Fig. 1, showing the position of the locking elements at the beginning o! a stroke of the piston: and` Fig. 3 is a partial section, showing they piston inits locked position in one cylinder end of a modiiied Jack. l

The embodiment oi theI invention illustrated in Figures l and 2 includes a cylinder Il and a hollow tubular piston II which is provided with a pair of circumferential spaced apart flanges I Ia and IIb. Apiston ring I2 is disposed between the flanges IIa and IIb for sealing the piston I I to the cylinder III. The .opposite ends of the cylinder I0 are threaded to receive' internally threaded caps I3 and Il.

The cap u is provided with a gland Ma' through which passes a piston rod I5 that has itsinner end connected to the piston II. 'I'he piston rod I 5 and the piston Il may be connected by a threaded plug I8 that is secured in the end of the piston and is received in an internally threaded recess IIa in theend of the pistonv rod I5.

`The cap I3 is provided with a coupling Ila through which liquid under pressure can be sup-V plied to the interior of the cylinder III to ,force the piston II to the right, as viewed in Figure 1. The cap I l is also provided with a coupling IIb through which iluid may be admitted to force the piston II to the left.

As best shown in Figure 2, the piston I I is provided with a plurality of radially extending openings or apertures I ic in its side walls for receiving one or more balls I1 that cooperate with the piston II and the cylinder I0 to lock these elements together at the end of the piston stroke. The apertures Ilc receive the balls I1 loosely so that the balls can move outwardly freely into engagement with a channel member I8 that is recess I8a and the Vapertures IIc form a compartment for receiving the balls I1 so that they may engage in the recess Ita and the aperture IIc simultaneously to lock the piston AII to the cylinder I0. The inclination of the wall I tb is such as to normally force the balls II-inwardly upon endwise movementfof the piston II.

-A cup-shaped auxiliary piston Il is siidabiy mounted in the interiorpf the piston II and is provided with suitable sealing rings-Ila to prevent leerer-emmerdes le.' er the pieten le ie eues met when it ie eerste extreme limit of movement. it will engage the balls I1 and force them into the recess Ila.

In order to retain the balls in position to be vensased by the piston 4I3, the left-hand end of 'receivingthe balls I1' which cooperate with another channel member (not shown) supported by the cap I4. The balls I1' are retained in the apertures IId by means of the enlarged head i3d on the threaied stud I3. The balls I1' can be be forced out of the apertures IId by the action of the piston I3. in traveling` to the right-hand end of its stroke.

In order to reduco friction, facilitate movement of the piston I I and reduce wear on the balls i I1 .andv I1' and the cylinder, I0, the piston is provided with retaining means Vwhich hold the balls I1 and ll'ywithin the periphery of the piston II until the piston II reaches substantially the end of its stroke. The retaining means may suitably consist of a pair of rings 2I and 22 disposed on opposite sides of the flanges I Ia and I Ib. The springs 23 and 24 are interposed between the flanges IIa and IIb and the rings 2| and 22 and normally urgethe rings into positions overlying the apertures IIc and IId.f-'When the piston- II moves toward the position shown in Fisures 1 and 2, the ring 2I.will engage the inner edge of the channel member I3 and the spring 23 will be compressed as the piston II moves to a position wherein the recesses llcare aligned with the recesses I3a of the channel member I3, thus uncovering the apertures Ilc and permite ting the balls to move into the recess I 3a. The ring 22 is displaced similarly upon movement of the pieten te the right.

In operation. when uid under pressure is sup- 'plied to the coupling Ila, theiluid will act on both the pistons II and I3, urging them toward As the piston II moves to the right, the retaining member 2I moves into position covering the apertures llc, retaining the bene l1 in the pieton ae the piston travels tothe right. As the piston I I approaches the end of its stroke to the right, the

piston I 3 urges the balls II' at the right-hand end of the piston II outwardly, but cannot do so because of the action of the retaining ring 22. When the ring 22 engages its corresponding channel member, it is stopped while the piston II continues to the right, uncovering the apertures IId therein and permitting the balls I1' to be forced into the channel member by the action of the piston I3, thereby locking the 'piston in'position. This condition remains until nuid .under is supplied at the coupling I4b whereafter the reverse of the operation described above takes place. y x If desired, the retaining Arings 2i and 22 and the springs 23 and 24 can be omitted in order to simplify the construction, but it is preferred to irliaclude them inview of the advantages described a ove.y Y

Figure 3 of the drawing illustrates a modified form of cylinder lock. In this device, the cylinder 33 is provided with a threaded end portion 3Iia for receiving an internally threaded cap 3l. 'I'he cap 3| is retained in sealing engagement with/the cylinder 30hy means of a threaded ring 32 and a sealing ring 33. The cap 3l is provided with a coupling 34 which communicates with the interior of the cylinder 30 through an aperture 34a. In this form of the invention, one or more locking balls 33 are supported by the cylinder 33 and the cap 3|, while the piston 33 is movable relatively thereto. As illustrated, the cap 34 is provided with a cup-shaped member 31 secured to the end of thecap in any suitable wam-such as by the set screw 33. The' member 31 is provided with one or more apertures 31a which taper in diameter from slightly larger than the diameter of the balls 35 at .their outer periphery to slightly less than the diametery of the balls 35 at the inner periphery so that the balls cannot fall into the cylinder. The side walls of the member 31 are spaced from the cylinder 30 a suillcient distancethat the balls 3l can be retracted fully, but cannot escape from between the member 31 and the cylinder 30. y

'I'he piston 36 may suitably consist of a cylindrical core menber 33 having a centrally disposed ilange 33a and oppositely threaded reduced endportions 39h and 33o. The center portion of the member 38 is adapted to receive a pair of' annulular members 40 and 4I. The member 4I includes adisclike portion 4 Ia which is sealed to the core member 33 by means of a sealing-ring 42 and is provided with an axially projecting ange 4Ib that engages the interior wall of the cylinder 30. The member 4I also includes an oppositely directed flange member 4Ic engaging the body of the core member 39 and being pro-v vided with a plurality of bores 4Id for receivingy it can enter the yspace between the cylinder 30 and the member 31 and urge the balls 35 radially inwardly. The inward movement of the balls 35 locks the piston 33 to the cylinder by forcing the balls in behind a flange 45 on a member 43 that is threaded on the reduced portion 39h. The flange 45 has an inclined inner and outer surface,

the inner surface Joining with a surfaceoi'i the n member 48 of reduced diameter providing a recess for reception of the balls 4Ib.

The oppositev end of the piston 36 is connected to the piston rod 41 by means of the threaded reduced portion 33e. The member 40 is supported on the member 33 in a manner similar to the member 4I and is normally urged against the piston rod 41 by means of the springs 43.

With the piston 33 in the position shown in Figure 3. the supply of fluid under pressure to the coupling 34 will urge the member 4I to the right, compressing the springs 43. Movement of the member 4I relatively to the piston 36 frees the balls 3l for outward movement by means of the inclined surface oi the flange 45, thereby freeing the entire piston 36 for movement to the right.

Upon return movement; of the piston 36 to the position shown in Figure 3, the flange 45 will strike the balls 35 rst and displace them outwardly. In this position,.the balls 35 obstruct the movementl of the member 4| so that it is3 stopped until the iiange 45 passes beneath the balls 35. When the flange 45 has passed the balls 35, the springs 43 urge the member 4| to the left and force the balls 35 radially inward behind the ange 45 to lock the piston 36 in position.

It will be understood that the constructions described above are susceptible to-cosiderable modification. For example, the ball-receiving` apertures may be substantially the same shape as the balls, that is, circular, or they may be annular or arcuate in order to permit the use of a plurality of balls so that relative rotation of the piston and the cylinder may be obtained. Likewise, the dimensions and shape of the various elements may be modified as the purpose demands.

The foregoing description is not intended to limit the present invention which extends to all changes, modications and equivalents comprehended within the scope of the appended claims.

What is claimed is: A

1. A piston lock for fluid actuated jacks comprising a cylinder having an internal recess adjacent one end thereof, a hollow piston slidable in saidcylinder having at least one opening through a side wall adjacent one end thereof,

l said opening and recess being alignedA when `the piston is at one end of its stroke, a locking member in said opening movable partially into said f recess when said recess and opening are in alignment, a second piston within and slidable axially of the mst-mentioned piston in response to fluid pressure thereon for engaging said locking member and forcing it partially into said recess, means slidable on the exterior of the rst-mentioned piston and biased to a'position for retaining said locking member within said opening, and means in said cylinder for displacing said slidable means at the said one end of the stroke to permit said locking member to enter said recess.

2. Piston lock for hydraulic and pneumatic Jacks which comprises a cylinder, a piston slidable therein, a plurality of perforations traversing the wall of the head of said piston, a plurality of corresponding sockets formedin at least one yend of said cylinder, said perforations and said sockets being adapted to register with each other so as to form a plurality of compartments when said piston is in one of its extreme postions with respect tosaid cylinder, a plurality of balls adaptsure prevailing in said cylinder, said balls being completely accommodated within said piston head while the same travels within said cylinder, said auxiliary element being adapted to penetrate into said auxiliary cavities and to make contact with said balls when said piston approaches the end of itsv stroke, to push said balls into said compartments when saidfirst mentioned cavities register with each other and, in its extreme position with respect to said piston head to close said compartments, meansto force said balls to enter said auxiliary cavities when said auxiliary element and said piston are displaced from their said extreme positions .under the action of fluid pressure admitted intosaid cylinder, and means to prevent said balls from falling out of said cavities in said piston head while the same is travelling.

3. Piston lock for hydraulic and pneumatic jacks which comprises a cylinder, a piston slidable therein, a plurality of perforations traversing the wall of the head of saidl piston, a plurality of corresponding sockets formed in at least one end of said cylinder, said perforations and said sockets being adapted to register with each other so as to form a plurality of compartments when said piston is in one of its extreme .positions with respect to said cylinder, a plurality `of balls adapted to fit said compartments, auxiliary cavities inside said piston head adjacent said rst mentioned cavities in the same and adapted to accommodate said balls completely within said piston head, an auxiliaryelement slidable in the hollow interior of said piston head,

means to subject said auxiliary element to the iiuid pressure prevailing in said cylinder, said balls being completely accommodated within said piston head while the same travels within said cylinder, said auxiliary element being adapted to penetrate into said auxiliary cavities and to make contact lwith said balls when said piston approaches the end of its stroke, to pushy said balls into said compartments when said rst mentioned cavities register with each other and, in its extreme position with respect to said piston head, to close said compartments, the portion of said sockets opposite to the adjacent end of said ed to fit said compartments, auxiliary cavities inside said piston head adjacent said iirst lmentioned cavities in the s'ame and adapted to accommodate said balls completely within said piston head, an auxiliary element associated with said piston head and capable of limited axial displacements with respect thereto, means to subject said auxiliary element to the iluid pres--` cylinder having a shallow 'concave curvature and the corresponding portion ofsaid perforations in said piston head being inclined toward the inside thereof so that the pressure exerted on said balls by said piston head in the direction of the distant end of said cylinder tends to force said balls into said auxiliary cavities, an annular sleeve slidably engaging the outer surface of said piston head adapted to cover said perforations, a stop member on the outer surface of said piston head between said perforations and the adiacent end o1' said piston head, and a spring urging said sleeve against said stop member, said sockets being adapted to engage said sleeve when said piston approaches the end ofits stroke and to push the same towards thel central portion of said piston head.

BENJAMIN N. ASHTON. NELSON G. KLING. 

